A significant amount of dentistry is done by the indirect method in which models or casts of the patient's upper and lower tooth structures are mounted on a dental articulator which has hinged frames that may be moved in a manner to simulate jaw movement. Great strides have been made in the taking and recording of jaw movement measurements and other information. This, in turn, increases the accuracy of the dental casts made from this information and ultimately effects the accuracy of the resulting jaw movement simulation when the casts are mounted on a dental articulator.
Typically, a dentist or his assistant will take a mold of the patient's teeth and then give the mold to a lab technician for the preparation of the dental cast. These models or dental casts are mounted on plates in an articulator in the laboratory. The casts are usually later transmitted to the dentist or orthodontist who uses them in an articulator in his office or work area, which is normally in a different location. The casts are usually used considerably when initially made, and then they are normally stored but used at later times as well.
The accuracy of the conclusions based on the jaw movement simulation with those models is dependent upon many factors. One such factor is the accuracy of the articulator itself. It is desirable that articulators of a given type be manufactured with sufficient accuracy and consistency that they are interchangeable. This enables dental casts first mounted in one articulator at one time to be used later on a different articulator at another time.
Various techniques have been utilized to improve the accuracy in the manufacture of articulators. Certain manufacturers of articulators attempt to overcome the interchangeability problem by providing auxiliary equipment such as binoculars and crosshairs in order to accurately adjust the mounting of a cast in an articulator to eliminate the effort of dimensional irregularities. These devices however, are costly and require considerable time in use.
In another approach set forth in U.S. Pat. No. 4,352,662, accuracy is obtained by recognizing the importance of certain relationships articulator frames and then using alignment blocks and extreme care in machining of the articulator frames. Naturally, as tolerance requirements are increased, the costs of machining are increased or else the quality control rejection rate is increased. In spite of these advances in accuracy and interchangeability, a need still exists for improvements in accuracy and in the cost of manufacture of dental articulators.